What size mini split do I need for a garage?

For an insulated garage: about 9,000 BTU for a 1-car garage, 12,000 BTU for most 2-car garages (9,000 under 400 sq ft), and 18,000 BTU for a 3-car garage (ENERGY STAR's sizing chart). For an uninsulated garage: 9,000 to 12,000 BTU for one car, 18,000 for two, 36,000 for three, or insulate first.

What size mini split for a 2-car garage?

12,000 BTU for an insulated 2-car garage of 400 to 550 sq ft (9,000 BTU is enough for a small 18 x 20 ft one). 18,000 BTU if it is not insulated.

What size mini split for a 500 sq ft garage?

12,000 BTU if the garage is insulated and finished. 18,000 BTU if it is not insulated. Insulating the door and ceiling first lets you buy the smaller unit.

What size mini split for a 3-car garage?

18,000 BTU if it is insulated (ENERGY STAR puts 700 to 1,000 sq ft at 18,000 BTU). An uninsulated 3-car garage comes to about 27,000 BTU by our rule, more than a 24,000 BTU unit makes, so insulate first or use a 36,000 BTU unit.

Is 12,000 BTU enough for a garage?

For an insulated 1- or 2-car garage up to about 550 sq ft, yes. For an uninsulated 2-car garage, or a 3-car garage, no: buy 18,000 BTU.

Can I run a mini split in a garage on 115 volts?

Yes, at 9,000 and 12,000 BTU. The Klimaire DIY 9,000 BTU and Perfect Aire Quick Connect 12,000 BTU run on 115 volts. It still needs its own circuit, not the garage outlet circuit. Units of 18,000 BTU and up need 230 volts.

Will a mini split heat a garage in winter?

Yes, if you pick a cold-climate unit sized for the heat it makes at 5°F. The Klimaire DIY 12,000 BTU makes 9,100 BTU of heat at 5°F; the Cooper & Hunter Hyper Heat 12,000 BTU makes 11,500 BTU (AHRI).

Is a mini split good for a garage workshop?

Yes. It heats and cools without ducts and runs quietly. Add 600 BTU for each extra person, keep dust and paint fumes away from the indoor unit, and rinse its filter often.

Do I need to insulate my garage before installing a mini split?

It is not required, but it usually pays. An insulated garage needs a smaller, cheaper unit, and it holds the temperature better. Start with the garage door and the ceiling.

What Is the Best Mini Split for a Garage?

An insulated garage needs about 9,000 BTU for one car, 12,000 BTU for most two-car garages (9,000 if it is under 400 sq ft, like 18 x 20 ft), and 18,000 BTU for three cars. If it is not insulated, plan on 9,000 to 12,000 BTU for one car, 18,000 for two and 36,000 for three, or insulate the door and ceiling first.^[1]

Best for a 2-car garage

Klimaire DIY 12,000 BTU, 230V

$1,459 on Amazon, October 17, 2026

For an insulated 2-car garage up to about 550 sq ft. A true DIY kit: 25-ft pre-charged lines that click together, no vacuum pump. Needs a 240-volt circuit.
Check price on Amazon
24 SEER2 · 9,100 BTU of heat at 5°F · cold-climate certified^[5]
Best for a 1-car garage

Klimaire DIY 9,000 BTU, 115V

$1,369 on Amazon, October 17, 2026

For an insulated 1-car garage. Runs on 115 volts, and it is a true DIY kit with 25-ft pre-charged lines.
Check price on Amazon
23 SEER2 · 7,100 BTU of heat at 5°F · cold-climate certified^[5]
Uninsulated 2-car or insulated 3-car

Klimaire DIY 18,000 BTU, 230V

$1,583.10 on Amazon, October 17, 2026

The size up when the table says 18,000. Same DIY quick-connect design, 13,600 BTU of heat at 5°F.
Check price on Amazon
23 SEER2 · 13,600 BTU of heat at 5°F · cold-climate certified^[5]
Best for hard winters

Cooper & Hunter Hyper Heat 12,000 BTU, 230V

$1,824.99 on Amazon, October 17, 2026

The most heat at 5°F of any 12,000 BTU unit here (11,500 BTU). The seller says it heats down to -22°F. Needs a pro to install.
Check price on Amazon
24 SEER2 · 11,500 BTU of heat at 5°F · cold-climate certified^[5]

Certified ratings are the AHRI Directory figures for the exact outdoor + indoor pair each listing names. Prices are Amazon's on October 17, 2026 and change often. Affiliate links; we earn a commission at no cost to you.

The four garage picks compared: install, certified SEER2 and heat at 5°F, price per 1,000 BTU of heat at 5°F, AHRI reference and price
Pick	Install	SEER2	Heat at 5°F	Per 1,000 BTU at 5°F	Price	Buy
Klimaire DIY 12,000 BTU, 230VBest for a 2-car garage · AHRI ref 218067069	DIY kit	24	9,100 BTU	$160	$1,459October 17, 2026	Check price
Klimaire DIY 9,000 BTU, 115VBest for a 1-car garage · AHRI ref 218067067	DIY kit	23	7,100 BTU	$193	$1,369October 17, 2026	Check price
Klimaire DIY 18,000 BTU, 230VUninsulated 2-car or insulated 3-car · AHRI ref 218067070	DIY kit	23	13,600 BTU	$116	$1,583.10October 17, 2026	Check price
Cooper & Hunter Hyper Heat 12,000 BTU, 230VBest for hard winters · AHRI ref 215864153	Pro required	24	11,500 BTU	$159	$1,824.99October 17, 2026	Check price

By Erin Rose · Updated October 17, 2026

01 / Size chart

Mini split size by garage

Insulated sizes come from ENERGY STAR's sizing chart (8-ft ceiling). There is no official chart for an uninsulated garage, so we add 50% and say so. Then buy the smallest size sold that covers the total.^[1]^[2]

Mini split size for 1-car, 2-car and 3-car garages, insulated and uninsulated
Garage	Floor area	Insulated: buy	Not insulated: buy
1-car12 x 20 ft · Angi average	240 sq ft	9,000 BTUchart: 6,000 BTU	9,000 BTU+50%: 9,000 BTU · computed by us
1-car, long12 x 24 ft	288 sq ft	9,000 BTUchart: 7,000 BTU	12,000 BTU+50%: 10,500 BTU · computed by us
1-car, wide14 x 24 ft	336 sq ft	9,000 BTUchart: 8,000 BTU	12,000 BTU+50%: 12,000 BTU · computed by us
2-car18 x 20 ft · Angi average	360 sq ft	9,000 BTUchart: 9,000 BTU	18,000 BTU+50%: 13,500 BTU · computed by us
2-car20 x 20 ft	400 sq ft	12,000 BTUchart: 10,000 BTU	18,000 BTU+50%: 15,000 BTU · computed by us
2-car, large22 x 22 ft	484 sq ft	12,000 BTUchart: 12,000 BTU	18,000 BTU+50%: 18,000 BTU · computed by us
3-car32 x 22 ft · Angi average	704 sq ft	18,000 BTUchart: 18,000 BTU	36,000 BTU+50%: 27,000 BTU · computed by us
3-car, large36 x 24 ft	864 sq ft	18,000 BTUchart: 18,000 BTU	36,000 BTU+50%: 27,000 BTU · computed by us

Garage sizes are Angi's averages and common sizes. Measure yours: length times width in feet. Sizes sold on Amazon jump 9,000 → 12,000 → 18,000 → 24,000 → 36,000 BTU.

Exactly 500 sq ft? What size mini split for 500 sq ft has every ENERGY STAR adjustment.

02 / Insulation

Insulated or not: why the size changes

An uninsulated garage gains heat through bare walls, the roof and a thin door, so the same floor area needs more capacity. ENERGY STAR's chart is written for rooms, not bare garages.^[1]

DOE says a common rule of one ton (12,000 BTU) per 400 to 500 sq ft "fails to take into account local climate and the efficiency of a house," and that one ton can cool 800 to 1,000 sq ft of a very efficient house. That is a 2-to-1 spread for the same floor area.^[3]

Our +50% rule for uninsulated garages sits inside that spread. For a 500 sq ft garage it gives 18,000 BTU. The two garage calculators we checked land at 18,000 to 24,000 BTU for that size (HVAC Base, Best Calculators).^[9]^[10]

Insulating first is often cheaper than buying the next size. NEEP's sizing guide says to fix insulation and air leaks before you size the equipment. For an exact number, an HVAC pro can run an ACCA Manual J load calculation.^[4]

03 / Winter heat

Heating a garage: check heat at 5°F, not the BTU on the box

A mini split's BTU number is its cooling size. In cold weather it makes less heat. AHRI certifies how much heat each unit makes at 5°F. The cold-climate units below keep 71% to 96% of their rated heat at 5°F.^[5]

For example, the Klimaire DIY 12,000 BTU makes 9,100 BTU of heat at 5°F. The Cooper & Hunter Hyper Heat 12,000 BTU makes 11,500 BTU, the most of any 12,000 BTU unit here. At 24,000 BTU, the Cooper & Hunter Hyper Heat makes 24,000 BTU at 5°F.^[5]

If you will heat the garage in a cold winter, compare the heat-at-5°F column, not the size. Every unit in the table carries the AHRI cold-climate designation.^[5]

HSPF2 is heating efficiency over a season. Higher means a lower power bill for the same heat.

04 / Certified units

Every cold-climate mini split we matched on Amazon, 9,000 to 24,000 BTU

14 units · October 17, 2026

In stock on Amazon on October 17, 2026, each matched to its exact outdoor + indoor pair in the AHRI Directory. Grouped by size; within a size, the most heat at 5°F first.^[5]

Cold-climate mini splits on Amazon with size, volts, install type, certified heat at 5°F, SEER2, HSPF2 and price
Unit	Volts	Install	Heat at 5°F	SEER2	HSPF2	Price	Buy
Pioneer Diamante9,000 BTU · ENERGY STAR	115V	Pro (standard lines)	7,300 BTU73% of rated	19	9.5	$858	Check price
Turbro Greenland9,000 BTU · ENERGY STAR	230V	Pro recommended	7,100 BTU71% of rated	23	9.5	$549.99	Check price
Klimaire DIY9,000 BTU · ENERGY STAR	115V	DIY kit	7,100 BTU71% of rated	23	9.5	$1,369	Check price
Cooper & Hunter Hyper Heat12,000 BTU · ENERGY STAR	230V	Pro required	11,500 BTU96% of rated	24	10.5	$1,824.99	Check price
Perfect Aire Quick Connect12,000 BTU · ENERGY STAR	115V	DIY kit	9,200 BTU77% of rated	22	9.5	$1,719.99	Check price
Turbro Greenland12,000 BTU · ENERGY STAR	230V	Pro recommended	9,100 BTU72% of rated	24	10	$699.99	Check price
Klimaire DIY12,000 BTU · ENERGY STAR	230V	DIY kit	9,100 BTU72% of rated	24	10	$1,459	Check price
Turbro Greenland12,000 BTU · ENERGY STAR	115V	Pro recommended	8,900 BTU72% of rated	23	10	$649.99	Check price
Klimaire DIY18,000 BTU · ENERGY STAR	230V	DIY kit	13,600 BTU72% of rated	23	10	$1,583.10	Check price
Cooper & Hunter Hyper Heat24,000 BTU · ENERGY STAR	230V	Pro required	24,000 BTU92% of rated	22.3	13.3	$2,879.99	Check price
Perfect Aire Quick Connect24,000 BTU · ENERGY STAR	230V	DIY kit	19,200 BTU80% of rated	22.5	9.5	$2,025.45	Check price
Klimaire DIY24,000 BTU · ENERGY STAR	230V	DIY kit	18,600 BTU74% of rated	23	9.5	$1,869	Check price
Senville LETO24,000 BTU	230V	Pro required	17,000 BTU71% of rated	18.7	9.3	$1,249.99	Check price
Cooper & Hunter MIA24,000 BTU	230V	Pro required	17,000 BTU71% of rated	18.7	9.3	$1,498.97	Check price

Heat at 5°F is the certified heating output on a 5°F day. DIY kits ship with pre-charged quick-connect lines. Pro units need an installer to vacuum and charge the lines.

05 / Power

115V or 230V in a garage?

Both need their own new circuit. Don't count on the garage outlets. The electrical code (NEC 210.11(C)(4)) sets aside a 20-amp, 120-volt circuit for the garage outlets, and MRCOOL's manual says to connect the unit only to its own branch circuit, shared with no other appliance.^[7]^[8]

A 115V unit, like the Klimaire DIY 9,000 BTU or the Perfect Aire Quick Connect 12,000 BTU, runs on a 120-volt circuit. A 230V unit needs a 240-volt circuit, like an electric dryer's. Every 18,000 and 24,000 BTU unit we list runs on 230 volts.^[6]

Plan on an electrician for the new circuit. Even for a DIY kit, MRCOOL's manual says the wiring must be installed by a licensed electrician.^[8]

06 / Safety

Garage safety

A mini split moves heat. It does not bring in fresh air, so it does nothing about car exhaust. Never run a car in a closed garage, and put a carbon monoxide alarm in any garage attached to the house.^[11]

Keep gas cans, paint and spray cans away from the indoor unit. MRCOOL's manual says not to install the unit where combustible gas can leak and not to use flammable sprays such as paint or lacquer near it. Its units use R-454B, a flammable refrigerant, and the manual says to mount the indoor unit at least 6 feet above the floor.^[8]

Do not tie the garage into your home's ducts. A ductless unit that serves only the garage keeps garage air out of the house.

07 / Workshop

For a garage workshop

Count the people and the heat. ENERGY STAR adds 600 BTU for each person over two who uses the room regularly. Power tools, a compressor or a welder add heat too.^[1]

Dust clogs the indoor unit's filter fast. Rinse it often, and keep sanding and sawdust away from the indoor unit.

If you spray paint or finishes in the shop, see the safety note above: keep fumes away from the unit.

More: which mini-split brands are really DIY · MRCOOL DIY vs EasyPro

08 / Who should buy which

Who should buy which

Insulated 1-car garage: Klimaire DIY 9,000 BTU. 115 V, DIY, $1,369.
Insulated 2-car garage: Klimaire DIY 12,000 BTU. DIY, 24 SEER2, $1,459.
2-car garage on a 115 V circuit: Perfect Aire Quick Connect 12,000 BTU. DIY on 115 V, $1,719.99.
Uninsulated 2-car or insulated 3-car garage: Klimaire DIY 18,000 BTU. DIY, 13,600 BTU at 5°F, $1,583.10.
Large or uninsulated garage on a DIY budget: Klimaire DIY 24,000 BTU. DIY, 18,600 BTU at 5°F, $1,869.
Hard winters, will pay a pro: Cooper & Hunter Hyper Heat 12,000 BTU. 11,500 BTU at 5°F, $1,824.99; Cooper & Hunter Hyper Heat 24,000 BTU makes 24,000 BTU at 5°F ($2,879.99).
Lowest price, will pay a pro: Turbro Greenland 12,000 BTU. $649.99, cold-climate certified.

09 / Questions

Frequently asked

What size mini split do I need for a garage?: For an insulated garage: about 9,000 BTU for a 1-car garage, 12,000 BTU for most 2-car garages (9,000 under 400 sq ft), and 18,000 BTU for a 3-car garage (ENERGY STAR's sizing chart). For an uninsulated garage: 9,000 to 12,000 BTU for one car, 18,000 for two, 36,000 for three, or insulate first.
What size mini split for a 2-car garage?: 12,000 BTU for an insulated 2-car garage of 400 to 550 sq ft (9,000 BTU is enough for a small 18 x 20 ft one). 18,000 BTU if it is not insulated.
What size mini split for a 500 sq ft garage?: 12,000 BTU if the garage is insulated and finished. 18,000 BTU if it is not insulated. Insulating the door and ceiling first lets you buy the smaller unit.
What size mini split for a 3-car garage?: 18,000 BTU if it is insulated (ENERGY STAR puts 700 to 1,000 sq ft at 18,000 BTU). An uninsulated 3-car garage comes to about 27,000 BTU by our rule, more than a 24,000 BTU unit makes, so insulate first or use a 36,000 BTU unit.
Is 12,000 BTU enough for a garage?: For an insulated 1- or 2-car garage up to about 550 sq ft, yes. For an uninsulated 2-car garage, or a 3-car garage, no: buy 18,000 BTU.
Can I run a mini split in a garage on 115 volts?: Yes, at 9,000 and 12,000 BTU. The Klimaire DIY 9,000 BTU and Perfect Aire Quick Connect 12,000 BTU run on 115 volts. It still needs its own circuit, not the garage outlet circuit. Units of 18,000 BTU and up need 230 volts.
Will a mini split heat a garage in winter?: Yes, if you pick a cold-climate unit sized for the heat it makes at 5°F. The Klimaire DIY 12,000 BTU makes 9,100 BTU of heat at 5°F; the Cooper & Hunter Hyper Heat 12,000 BTU makes 11,500 BTU (AHRI).
Is a mini split good for a garage workshop?: Yes. It heats and cools without ducts and runs quietly. Add 600 BTU for each extra person, keep dust and paint fumes away from the indoor unit, and rinse its filter often.
Do I need to insulate my garage before installing a mini split?: It is not required, but it usually pays. An insulated garage needs a smaller, cheaper unit, and it holds the temperature better. Start with the garage door and the ceiling.

How we did this

Method

How we sized the garages and picked the units

Sizing. Insulated sizes are ENERGY STAR's room air conditioner chart, read on October 7, 2026, applied to Angi's average and common garage sizes. The +50% for an uninsulated garage is our rule (see the section above); no agency publishes one.

Buying rule. We round each total up to the next size sold. The sizes come from every mini split we matched on Amazon: 9,000, 12,000, 18,000, 24,000 and 36,000 BTU.

Units. We list every cold-climate-certified mini split from 9,000 to 24,000 BTU that we matched to its exact AHRI pair and that had an Add to Cart button on Amazon on October 17, 2026. AHRI certifies the cooling size, SEER2, HSPF2 and heat at 5°F.

Picks. For each garage size, the pick is the DIY kit with the highest certified SEER2. These match our picks on the 500 sq ft sizing page and the best mini-splits page. The winter pick is the 12,000 BTU unit with the most certified heat at 5°F.

Limits

What we checked, and what we did not

We checked:

ENERGY STAR's sizing chart and Angi's garage sizes, read October 7, 2026.
AHRI Directory ratings for the exact outdoor + indoor pair of every unit listed, queried by model number.
Amazon price for each listing from Amazon's product data, and a live check that each listing had an Add to Cart button, on October 17, 2026.

We did not check:

No agency publishes a size rule for uninsulated garages. Our +50% rule is a reasoned estimate, not a load calculation.
We did not install or test any unit. Heat figures are AHRI-certified lab ratings.
Your garage's real load depends on climate, door, ceiling and sun. An ACCA Manual J calculation gives the exact number.

References

Sources

12 references · checked October 17, 2026

1
ENERGY STAR: Room Air Conditioners — "Properly Sized Room Air Conditioners" (sizing chart and adjustments)

Read October 7, 2026. Chart rows, the 8-ft ceiling basis, and the +600 BTU per extra person adjustment.
2
Angi: Average Garage Size (1-, 2- and 3-car)

Updated July 9, 2026; read October 7, 2026. Averages 12 x 20, 18 x 20, 32 x 22 ft; common sizes 12 x 24, 14 x 24, 20 x 20, 22 x 22, 36 x 24 ft.
3
U.S. Department of Energy, Energy Saver: Home Heating and Cooling

Read October 7, 2026. One ton per 400-500 sq ft "fails to take into account local climate and the efficiency of a house"; one ton can condition 800-1,000 sq ft of a very efficient house; use ACCA Manual J.
4
NEEP: Guide to Sizing & Selecting Air-Source Heat Pumps in Cold Climates (rev 04/08/20)

Read October 7, 2026. Fix insulation and air leaks before sizing; use ACCA Manual J.
5
AHRI Directory of Certified Product Performance — ductless mini-split heat pumps

Reference numbers: 217048740 (Pioneer Diamante 9,000 115V), 217222925 (Turbro Greenland 9,000 230V), 218067067 (Klimaire DIY 9,000 115V), 215864153 (Cooper & Hunter Hyper Heat 12,000 230V), 218072567 (Perfect Aire Quick Connect 12,000 115V), 217222927 (Turbro Greenland 12,000 230V), 218067069 (Klimaire DIY 12,000 230V), 217222926 (Turbro Greenland 12,000 115V), 218067070 (Klimaire DIY 18,000 230V), 215864155 (Cooper & Hunter Hyper Heat 24,000 230V), 217747132 (Perfect Aire Quick Connect 24,000 230V), 218067071 (Klimaire DIY 24,000 230V), 215735291 (Senville LETO 24,000 230V), 216623807 (Cooper & Hunter MIA 24,000 230V).
6
Amazon listings for the units above (14)

Price and offer read October 17, 2026; buy box checked live the same day. Listing text read October 2, 2026.
7
NEC 2020 210.11(C)(4), garage branch circuits (reprinted by Leviton with NFPA permission)

Read October 7, 2026. "At least one 120-volt, 20-ampere branch circuit ... for attached garages ... This circuit shall have no other outlets."
8
MRCOOL DIY Easy Pro installation & owner's manual (version August 5, 2026)

Read October 7, 2026. "Only connect the unit to an individual branch circuit outlet. Do not connect another appliance to that outlet"; wiring "must be installed by a licensed electrician"; do not install where combustible gas may leak; no flammable sprays near the unit; indoor unit at least 6.0 ft above the floor (R-454B flammable-refrigerant warnings).
9
HVAC Base: Mini Split Sizing Calculator (garage examples)

Read October 7, 2026. 480 sq ft two-car garage: 18,000 BTU insulated; 21,000 uninsulated in a hot climate.
10
Best Calculators: Mini Split Size Calculator (garage example)

Read October 7, 2026. 500 sq ft garage, 10-ft ceiling, warm climate, high sun: 24,000 BTU.
11
EPA: Top tips to prevent carbon monoxide poisoning in your home, workshop or garage

"Never leave a parked vehicle motor running in a garage or other enclosed or even partially enclosed space."
12
Verified HVAC Data methodology

How certified ratings are handled.